L-threonine is an essential amino acid. It is important for regulating protein balance in the body. This amino acid is a precursor to serine and glycine. These are two other amino acids necessary for muscle tissue production. L-threonine supports digestive function, immune system, liver and cardiovascular function and the central nervous system.
L-threonine and the digestive system
A large portion of l-threonine is absorbed in the upper reaches of the small intestine (ileum). Here this amino acid is used to protect the digestive tract. Threonine is needed to produce the mucus gel layer that covers the digestive tract. This mucus is a barrier to digestive enzymes that can damage the intestines. Threonine is also used in other endogenous secretions. Hence, this amino acid is important for supporting healthy gut function.
Animal studies involving chickens, pigs, and rats have found that a low threonine diet leads to digestive problems and a reduction in immune function1, 2, 3. This is believed to be due to a decline in the gut mucus barrier. Not only does this negatively affect the immune system, it also disrupts nutrient absorption. This can lead to a cascade of health problems.
L-threonine and immune system support
L-threonine helps to produce antibodies to boost the immune system. The thymus gland responsible for synthesising infection-fighting T-lymphocytes (T-cells) utilises this amino acid. Ensuring that the body has enough threonine to support immune function is important to safeguard against disease and illness.
L-threonine and liver health
Threonine works together with the amino acids methione and aspartic acid to support the liver. These amino acids help to facilitate lipotropic function. This is the process needed to digest fatty acids and fats. In the absence of sufficient threonine the liver would become overwhelmed by fats. Consequently resulting in liver failure.
L-threonine and bone/connective tissue health
Structural proteins collagen and elastin need threonine. This amino acid is the precursor for serine and glycine. These two amino acids are necessary to create these proteins. Collagen it the most abundant structural protein in the body. It is vital for connective tissue formation and maintenance. Thus, threonine helps to support strong and elastic muscles and connective tissue throughout the body. This includes the heart. Furthermore, this amino acid can assist to accelerate healing of wounds and bones following injury.
L-threonine and cognitive function
Threonine is in high concentrations in the central nervous system. There has been interest in the use of this amino acid in the treatment of Amyotrophic Lateral Sclerosis (Lou Gherigs Disease)4, 5. However, further studies are necessary.
Other research has also indicated the potential of threonine to help reduce some of the symptoms of Multiple Sclerosis, including a reduction in spastcity6. Many studies have found that threonine can help to fight depression and can improve mental health7, 8.
Symptoms of L-threonine deficiency
Digestion difficulties, emotional agitation, confusion and a fatty liver are common symptoms of a threonine deficiency. Threonine is usually abundant in a balanced diet. Consequently, deficiencies are rare. However, vegans and strict vegetarians may want to consider a supplement. This is because the highest concentrations of this amino acid are found in meat and dairy products. This amino acid is available in protein bars/powders and amino acid capsules/tablets.
Dietary sources of L-threonine
Some of the highest concentrations of this essential amino acid are found in fish, meat, meat products, dairy, eggs, carrots, and bananas. Nuts, beans, seeds and other vegetables do contain threonine. However, not in as high concentrations. Adults need approximately 15mg of this amino acid per kilogram of body weight daily for optimal functioning9.
In summary, l-threonine is an important essential amino acid. It has a range of roles in the human body. It helps to support the immune system and healthy digestion. This amino acid is also essential for tissue development and maintenance. Therefore, it plays a key role in heart and liver health. In addition, the central nervous system also requires adequate concentrations of this amino acid. This helps to support cognitive function.
Most people acquire healthy levels of threonine through their diet. In cases where a deficiency is identified supplements may be required. However, it is important to only take threonine supplementation under the guidance of a medical practitioner. Too much of this amino acid is dangerous. It can cause liver damage and ammonia toxicity.
- “ Azzam M, et al. (2011). Effect of supplemental L-threonine on mucin 2 gene expression and intestine mucosal immune and digestive enzymes activities of laying hens in environments with high temperature and humidity. Poultry Science. Volume 90, Issue 10 (pp. 2251-2256).” ↩
- “Hamard A, et al. (2010). A moderate threonine deficiency affects gene expression profile, paracellular permeability and glucose absorption capacity in the ileum of piglets. Journal of Nutritional Biochemistry. Volume 21, Issue 10, (pp. 914-921).” ↩
- “Faure M, et al. (2005). Dietary threonine restriction specifically reduces intestinal mucin synthesis in rats. Journal of Nutrition. Volume 135, Issue 3, (pp.486–91).” ↩
- Blin, O et al. (1992). A double-blind placebo-controlled trial of L-threonine in amyotrophic lateral sclerosis. Journal of Neurology. Volume 239, Issue 2, (pp. 79-81).” ↩
- ”Tandan, R et al. (1996). A controlled trial of amino acid therapy in amyotropic lateral sclerosis: I. Clinical, functional and maximum isometric torque data. Neurology. Volume 47, Issue 5, (pp. 1220-6).” ↩
- “Hauser, S et al. (1992). An antispasticity effect of threonine in multiple sclerosis. Archives in Neurology. Volume 49, Issue 9, (pp. 923-6).”. ↩
- “Chalexka-Franaszek, E. and Chuang DM. (1999). Lithium activates the serine/threonine kinase Akt-1 and suppresses glutamate-induced inhibition of Akt-1 activity in neurons. Proceedings of the National Academy of Sciences of the United States of America. Volume 96, issue 15, (pp. 8745-60)”. ↩
- “Beaulieu, J. (2011). A role for Akt and glycogen synthase kinase-3 as integrators of dopamine and serotonin neurotransmission in mental health. Journal of Psychiatry & Neuroscience. Volume 37, Issue 1, (pp.7-16).” ↩
- “Sudhir B, et al. (2002). Threonine requirement of healthy adults, derived with a 24-h indicator amino acid balance technique. American Journal of Clinical Nutrition. Volume 75, Issue 4, (pp.698-704).” ↩